The segmentation is done completely in software. The
driver creates several MPDUs out of a single large send.
Each MPDU is a newly allocated SKB.
A page is allocated to create the headers that need to be
duplicated (SNAP / IP / TCP). The WiFi header is in the
header of the newly created SKBs.
type=feature
Change-Id: I238ffa79cacc5bbdacdfbf3e9673c8d4f02b462a
Signed-off-by: Emmanuel Grumbach <emmanuel.grumb...@intel.com>
---
drivers/net/wireless/iwlwifi/mvm/tx.c | 513 +++++++++++++++++++++++++++++++---
1 file changed, 481 insertions(+), 32 deletions(-)
diff --git a/drivers/net/wireless/iwlwifi/mvm/tx.c
b/drivers/net/wireless/iwlwifi/mvm/tx.c
index 90f0ea1..a63686c 100644
--- a/drivers/net/wireless/iwlwifi/mvm/tx.c
+++ b/drivers/net/wireless/iwlwifi/mvm/tx.c
@@ -65,6 +65,7 @@
#include <linux/ieee80211.h>
#include <linux/etherdevice.h>
#include <net/tcp.h>
+#include <net/ip.h>
#include "iwl-trans.h"
#include "iwl-eeprom-parse.h"
@@ -435,32 +436,471 @@ int iwl_mvm_tx_skb_non_sta(struct iwl_mvm *mvm, struct
sk_buff *skb)
return 0;
}
+/*
+ * Update the IP / TCP headers and recompute the IP header CSUM +
+ * pseudo header CSUM.
+ */
+static void iwl_update_ip_tcph(void *iph, struct tcphdr *tcph, bool ipv6,
+ unsigned int len, unsigned int tcp_seq_offset,
+ u16 num_segment)
+{
+ be32_add_cpu(&tcph->seq, tcp_seq_offset);
+
+ if (ipv6) {
+ struct ipv6hdr *iphv6 = iph;
+
+ iphv6->payload_len = cpu_to_be16(len + tcph->doff * 4);
+
+ /* Compute CSUM on the the pseudo-header */
+ tcph->check = ~csum_ipv6_magic(&iphv6->saddr, &iphv6->daddr,
+ len + tcph->doff * 4,
+ IPPROTO_TCP, 0);
+ } else {
+ struct iphdr *iphv4 = iph;
+
+ iphv4->tot_len =
+ cpu_to_be16(len + tcph->doff * 4 + iphv4->ihl * 4);
+ be16_add_cpu(&iphv4->id, num_segment);
+ ip_send_check(iphv4);
+
+ /* Compute CSUM on the the pseudo-header */
+ tcph->check = ~csum_tcpudp_magic(iphv4->saddr, iphv4->daddr,
+ len + tcph->doff * 4,
+ IPPROTO_TCP, 0);
+ }
+}
+
+/**
+ * struct iwl_lso_splitter - state of the split.
+ * @linear_payload_len: The length of the payload inside the header of the
+ * original GSO skb.
+ * @gso_frag_num: The fragment number from which to take the data in the
+ * original GSO skb.
+ * @gso_payload_len: The length of the payload in the original GSO skb.
+ * @gso_payload_pos: The incrementing position in the payload of the original
+ * GSO skb.
+ * @gso_offset_in_page: The offset in the page of &gso_frag_num.
+ * @gso_current_frag_size: The size of &gso_frag_num.
+ * @gso_offset_in_frag: The offset in the &gso_frag_num.
+ * @frag_in_mpdu: The index of the frag inside the new (split) MPDU.
+ * @mss: The maximal segment size.
+ * @si: Points to the the shared info of the original GSO skb.
+ * @ieee80211_hdr *hdr: Points to the WiFi header.
+ * @gso_nr_frags: The number of frags in the original GSO skb.
+ * @wifi_hdr_iv_len: The length of the WiFi header including IV.
+ * @tcp_fin: True if TCP_FIN is set in the original GSO skb.
+ * @tcp_push: True if TCP_PSH is set in the original GSO skb.
+ */
+struct iwl_lso_splitter {
+ unsigned int linear_payload_len;
+ unsigned int gso_frag_num;
+ unsigned int gso_payload_len;
+ unsigned int gso_payload_pos;
+ unsigned int gso_offset_in_page;
+ unsigned int gso_current_frag_size;
+ unsigned int gso_offset_in_frag;
+ unsigned int frag_in_mpdu;
+ unsigned int mss;
+ struct skb_shared_info *si;
+ struct ieee80211_hdr *hdr;
+ u8 gso_nr_frags;
+ u8 wifi_hdr_iv_len;
+ bool tcp_fin;
+ bool tcp_push;
+};
+
+/*
+ * Adds a TCP segment from skb_gso to skb. All the state is taken from
+ * and fed back to p. This function takes care about the payload only.
+ * This MSDU might already have msdu_sz bytes of payload that come from
+ * the original GSO skb's header.
+ */
+static unsigned int
+iwl_add_tcp_segment(struct iwl_mvm *mvm, struct sk_buff *skb_gso,
+ struct sk_buff *skb, struct iwl_lso_splitter *p,
+ unsigned int msdu_sz)
+{
+ while (msdu_sz < p->mss) {
+ unsigned int frag_sz =
+ min_t(unsigned int, p->gso_current_frag_size,
+ p->mss - msdu_sz);
+
+ if (p->frag_in_mpdu >= mvm->trans->max_skb_frags)
+ return msdu_sz;
+
+ skb_add_rx_frag(skb, p->frag_in_mpdu,
+ skb_frag_page(&p->si->frags[p->gso_frag_num]),
+ p->gso_offset_in_page, frag_sz, 0);
+
+ /* We just added one frag to the mpdu ... */
+ p->frag_in_mpdu++;
+
+ /* ... which is frag_sz byte long ... */
+ msdu_sz += frag_sz;
+
+ /* ... we progress inside the gso frag ... */
+ p->gso_offset_in_page += frag_sz;
+
+ /* ... which is now getting smaller ... */
+ p->gso_current_frag_size -= frag_sz;
+
+ /* ... and we also progress in the global pos counting. */
+ p->gso_payload_pos += frag_sz;
+
+ /*
+ * This frag has some more bytes that can't fit into this MSDU,
+ * get a new one, and take a ref since this frag will be
+ * attached to two different skbs.
+ */
+ if (p->gso_current_frag_size) {
+ skb_frag_ref(skb_gso, p->gso_frag_num);
+ break;
+ }
+
+ /* We exhausted this frag go the next one ... */
+ p->gso_frag_num++;
+
+ /* ... if it exists ... */
+ if (p->gso_frag_num == p->gso_nr_frags)
+ break;
+
+ /* ... consider its full size ... */
+ p->gso_current_frag_size =
+ skb_frag_size(&p->si->frags[p->gso_frag_num]);
+ /* ... and start from its beginning. */
+ p->gso_offset_in_page =
+ p->si->frags[p->gso_frag_num].page_offset;
+ }
+ return msdu_sz;
+}
+
+/* Hack to compute the CSUM in software. For early testing */
+static __sum16
+iwl_sw_tcp_csum_offload(struct sk_buff *skb,
+ int tcph_offset, int len, int tcp_hdrlen)
+{
+ struct sk_buff *skb1;
+ __wsum csum;
+
+ len += tcp_hdrlen;
+ skb1 = alloc_skb(len, GFP_ATOMIC);
+ BUG_ON(!skb1);
+
+ skb_copy_bits(skb, tcph_offset, skb_put(skb1, len), len);
+
+ skb_set_transport_header(skb1, 0);
+ skb1->csum_start = (unsigned char *)tcp_hdr(skb1) - skb1->head;
+ csum = skb_checksum(skb1, skb_checksum_start_offset(skb1),
+ skb1->len - skb_checksum_start_offset(skb1),
+ 0);
+ dev_kfree_skb(skb1);
+
+ return csum_fold(csum);
+}
+
+static u8 *get_page_pos(struct page **page, u8 *page_pos, size_t len)
+{
+ if (!*page)
+ goto alloc;
+
+ if (page_pos + len < (u8 *)page_address(*page) + PAGE_SIZE)
+ return page_pos;
+
+ __free_pages(*page, 0);
+
+alloc:
+ *page = alloc_pages(GFP_ATOMIC, 0);
+ if (!*page)
+ return NULL;
+
+ return page_address(*page);
+}
+
+static int iwl_add_msdu(struct iwl_mvm *mvm, struct sk_buff *skb_gso,
+ struct sk_buff *skb, struct page **hdr_page,
+ u8 **hdr_page_pos, int ip_id,
+ struct iwl_lso_splitter *p)
+{
+ unsigned int tcp_seg_sz, snap_ip_tcp_len, copy_sz = 0;
+ bool ipv6 = p->si->gso_type & SKB_GSO_TCPV6;
+ u8 *start_hdr;
+ struct tcphdr *tcph;
+ struct iphdr *iph;
+
+ snap_ip_tcp_len =
+ 8 + skb_network_header_len(skb_gso) + tcp_hdrlen(skb_gso);
+ copy_sz = min_t(unsigned int, p->linear_payload_len, p->mss);
+
+ *hdr_page_pos =
+ get_page_pos(hdr_page, *hdr_page_pos,
+ snap_ip_tcp_len + copy_sz +
+ sizeof(struct ethhdr) + 4);
+ if (!*hdr_page_pos)
+ return -ENOMEM;
+
+ start_hdr = *hdr_page_pos;
+
+ /*
+ * Copy SNAP / IP / TCP headers from the original GSO skb to the
+ * header page.
+ */
+ skb_copy_bits(skb_gso, p->wifi_hdr_iv_len,
+ *hdr_page_pos, snap_ip_tcp_len);
+
+ *hdr_page_pos += 8;
+
+ iph = (void *)*hdr_page_pos;
+ *hdr_page_pos += skb_network_header_len(skb_gso);
+
+ tcph = (void *)*hdr_page_pos;
+ *hdr_page_pos += tcp_hdrlen(skb_gso);
+
+ /*
+ * If the original GSO skb had more than MSS bytes of payload in its
+ * header, consume it now.
+ */
+ if (copy_sz) {
+ /*
+ * Since we copy from the tail pointer and don't update it,
+ * we can't have more than 1 mss in the linear_payload_len
+ * at this stage. Hence the limitation of 2 MSS in
+ * iwl_mvm_tx_tso.
+ */
+ memcpy(*hdr_page_pos, skb_tail_pointer(skb_gso), copy_sz);
+ *hdr_page_pos += copy_sz;
+ p->gso_payload_pos += copy_sz;
+ p->linear_payload_len -= copy_sz;
+ }
+
+ /* Add frag for SNAP / IP / TCP headers and possibly some payload .. */
+ get_page(*hdr_page);
+ skb_add_rx_frag(skb, p->frag_in_mpdu, *hdr_page,
+ (u8 *)start_hdr - (u8 *)page_address(*hdr_page),
+ *hdr_page_pos - start_hdr, 0);
+ p->frag_in_mpdu++;
+
+ /* .. and now add the payload coming from the frags. */
+ tcp_seg_sz = iwl_add_tcp_segment(mvm, skb_gso, skb, p, copy_sz);
+
+ iwl_update_ip_tcph(iph, tcph, ipv6, tcp_seg_sz,
+ p->gso_payload_pos - tcp_seg_sz, ip_id);
+
+ /* Last segment, apply the TCP flags that may have been delayed */
+ if (p->gso_payload_pos == p->gso_payload_len) {
+ if (p->tcp_push)
+ tcph->psh = 1;
+ if (p->tcp_fin)
+ tcph->fin = 1;
+ }
+
+ if (IWL_MVM_SW_TX_CSUM_OFFLOAD)
+ tcph->check =
+ iwl_sw_tcp_csum_offload(skb, skb->len -
+ tcp_seg_sz -
+ tcp_hdrlen(skb_gso),
+ tcp_seg_sz,
+ tcp_hdrlen(skb_gso));
+
+ return 0;
+}
+
static int iwl_mvm_tx_tso(struct iwl_mvm *mvm, struct sk_buff *skb_gso,
struct ieee80211_sta *sta,
struct sk_buff_head *mpdus_skb)
{
- struct sk_buff *tmp, *next;
- char cb[sizeof(skb_gso->cb)];
+ struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb_gso);
+ struct ieee80211_key_conf *keyconf = info->control.hw_key;
+ struct ieee80211_hdr *wifi_hdr = (void *)skb_gso->data;
+ bool ipv6 = skb_shinfo(skb_gso)->gso_type & SKB_GSO_TCPV6;
+ struct iwl_lso_splitter s = {};
+ struct page *hdr_page;
+ unsigned int mpdu_sz;
+ u8 *hdr_page_pos;
+ int i, ret;
+
+ s.si = skb_shinfo(skb_gso);
+ s.mss = skb_shinfo(skb_gso)->gso_size;
+ s.gso_nr_frags = skb_shinfo(skb_gso)->nr_frags;
+ s.linear_payload_len = skb_tail_pointer(skb_gso) -
+ skb_transport_header(skb_gso) - tcp_hdrlen(skb_gso);
+ s.gso_payload_len = s.linear_payload_len + skb_gso->data_len;
+
+ /* more than 2 * mss in the header or no frags ? segment w/o GSO */
+ if (s.linear_payload_len >= 2 * s.mss || !skb_gso->data_len) {
+ struct sk_buff *tmp, *next;
+ char cb[sizeof(skb_gso->cb)];
+
+ memcpy(cb, skb_gso->cb, sizeof(cb));
+ next = skb_gso_segment(skb_gso, 0);
+ if (IS_ERR(next))
+ return -EINVAL;
+ else if (next)
+ consume_skb(skb_gso);
+
+ while (next) {
+ tmp = next;
+ next = tmp->next;
+ memcpy(tmp->cb, cb, sizeof(tmp->cb));
+
+ tmp->prev = NULL;
+ tmp->next = NULL;
+
+ __skb_queue_tail(mpdus_skb, tmp);
+ }
+ return 0;
+ }
+
+ /*
+ * We got an GSO skb that may or may not have payload in its header.
+ * Re-use the same skb and chop the payload that can't fit into 1 MSS.
+ * First take the payload from the header...
+ */
+ mpdu_sz = min_t(unsigned int, s.linear_payload_len, s.mss);
+ s.linear_payload_len -= mpdu_sz;
+ skb_gso->data_len = 0;
+
+ /*
+ * ... and add now payload from the frags to get up to 1 MSS.
+ * If we have one mss already, mpdu_sz will be s.mss and
+ * this loop won't do much.
+ * Make sure we don't go beyond the limit of the origin GSO
+ * skb.
+ */
+ s.gso_offset_in_frag = 0;
+ while (s.gso_frag_num < s.gso_nr_frags &&
+ s.gso_frag_num <= mvm->trans->max_skb_frags) {
+ unsigned int frag_sz =
+ skb_frag_size(&s.si->frags[s.gso_frag_num]);
+
+ if ((s.mss - mpdu_sz) >= frag_sz) {
+ /* there is enough room for this entire frag */
+ mpdu_sz += frag_sz;
+ skb_gso->data_len += frag_sz;
+ s.gso_frag_num++;
+ continue;
+ }
- memcpy(cb, skb_gso->cb, sizeof(cb));
- next = skb_gso_segment(skb_gso, 0);
- if (IS_ERR(next))
+ /*
+ * Only part of this frag will fit and
+ * we now have a complete mss
+ */
+ s.gso_offset_in_frag = s.mss - mpdu_sz;
+ skb_gso->data_len += (s.mss - mpdu_sz);
+ mpdu_sz = s.mss;
+ break;
+ }
+
+ /* We have only one mss or even less? */
+ if (WARN(s.gso_frag_num == s.gso_nr_frags,
+ "frag: %d payload: %d\n", s.gso_frag_num, s.gso_payload_len))
return -EINVAL;
- else if (next)
- consume_skb(skb_gso);
- while (next) {
- tmp = next;
- next = tmp->next;
- memcpy(tmp->cb, cb, sizeof(tmp->cb));
+ /* remember the size of the remainder of the frag */
+ s.gso_current_frag_size = skb_frag_size(&s.si->frags[s.gso_frag_num]) -
+ s.gso_offset_in_frag;
+
+ /* shorten the skb_gso's frag to fit the mss */
+ skb_frag_size_set(&s.si->frags[s.gso_frag_num], s.gso_offset_in_frag);
+
+ /* translate to offset from the start of the page */
+ s.gso_offset_in_page =
+ s.gso_offset_in_frag + s.si->frags[s.gso_frag_num].page_offset;
+
+ /* remove all the other frags from skb_gso */
+ skb_shinfo(skb_gso)->nr_frags = s.gso_frag_num + 1;
+
+ /* FIXME: do we need to ref the last frag if no bytes of it were added
+ * to skb_gso: e.g. when the previous segment was completely consumed
+ * closed the first MSS?
+ */
+
+ /* take a temp ref to the last frag */
+ skb_frag_ref(skb_gso, s.gso_frag_num);
+
+ /* update the skb_gso's length fields */
+ skb_gso->len -= (s.gso_payload_len - mpdu_sz);
+
+ /*
+ * If there is still some payload in the header, update the tail to the
+ * end of MSS.
+ */
+ if (s.linear_payload_len)
+ skb_gso->tail -= s.linear_payload_len;
+
+ /*
+ * Clear the bits in the TCP header that we delay for
+ * the last segment.
+ */
+ s.tcp_push = tcp_hdr(skb_gso)->psh;
+ s.tcp_fin = tcp_hdr(skb_gso)->fin;
+ tcp_hdr(skb_gso)->psh = 0;
+ tcp_hdr(skb_gso)->fin = 0;
+
+ /* update the IP / TCP header with the new length */
+ iwl_update_ip_tcph(ip_hdr(skb_gso), tcp_hdr(skb_gso),
+ ipv6, mpdu_sz, 0, 0);
+
+ if (IWL_MVM_SW_TX_CSUM_OFFLOAD)
+ tcp_hdr(skb_gso)->check =
+ iwl_sw_tcp_csum_offload(skb_gso,
+ (u8 *)tcp_hdr(skb_gso) -
+ (u8 *)skb_gso->data,
+ mpdu_sz, tcp_hdrlen(skb_gso));
+
+ __skb_queue_tail(mpdus_skb, skb_gso);
+
+ /* mss bytes have been consumed from the data */
+ s.gso_payload_pos = s.mss;
+ i = 0;
+
+ hdr_page = NULL;
+ hdr_page_pos = get_page_pos(&hdr_page, NULL, 1);
+ if (!hdr_page_pos)
+ return -ENOMEM;
+
+ s.hdr = wifi_hdr;
+ s.wifi_hdr_iv_len = ieee80211_hdrlen(wifi_hdr->frame_control);
+ if (keyconf && (keyconf->cipher == WLAN_CIPHER_SUITE_CCMP ||
+ keyconf->cipher == WLAN_CIPHER_SUITE_CCMP_256))
+ s.wifi_hdr_iv_len += IEEE80211_CCMP_HDR_LEN;
+
+ while (s.gso_payload_pos < s.gso_payload_len) {
+ struct sk_buff *skb = dev_alloc_skb(s.wifi_hdr_iv_len);
+ int l;
+
+ s.frag_in_mpdu = 0;
- tmp->prev = NULL;
- tmp->next = NULL;
+ if (WARN_ON(s.gso_frag_num >= s.gso_nr_frags))
+ break;
+
+ if (!skb) {
+ ret = -ENOMEM;
+ goto out;
+ }
- __skb_queue_tail(mpdus_skb, tmp);
+ memcpy(skb->cb, skb_gso->cb, sizeof(skb->cb));
+
+ /* new MPDU - add WiFi header + IV */
+ memcpy(skb_put(skb, s.wifi_hdr_iv_len),
+ wifi_hdr, s.wifi_hdr_iv_len);
+
+ l = iwl_add_msdu(mvm, skb_gso, skb, &hdr_page,
+ &hdr_page_pos, i++, &s);
+ if (l < 0) {
+ skb_queue_purge(mpdus_skb);
+ ret = l;
+ goto out;
+ }
+
+ __skb_queue_tail(mpdus_skb, skb);
}
- return 0;
+ ret = 0;
+
+out:
+ if (hdr_page)
+ __free_pages(hdr_page, 0);
+ return ret;
}
static int iwl_skb_ensure_writable(struct sk_buff *skb, int write_len)
@@ -564,6 +1004,26 @@ drop:
return -1;
}
+static int iwl_mvm_tx_csum_and_send(struct iwl_mvm *mvm, struct sk_buff *skb,
+ struct ieee80211_sta *sta)
+{
+ if (skb->ip_summed == CHECKSUM_PARTIAL &&
+ IWL_MVM_SW_TX_CSUM_OFFLOAD) {
+ int offs = skb_checksum_start_offset(skb);
+ int csum_offs = offs + skb->csum_offset;
+ __wsum csum;
+
+ if (iwl_skb_ensure_writable(skb, csum_offs + sizeof(__sum16)))
+ return -1;
+
+ csum = skb_checksum(skb, offs, skb->len - offs, 0);
+
+ *(__sum16 *)(skb->data + csum_offs) = csum_fold(csum);
+ }
+
+ return iwl_mvm_tx_mpdu(mvm, skb, sta);
+}
+
/*
* Sets the fields in the Tx cmd that are crypto related
*/
@@ -581,26 +1041,15 @@ int iwl_mvm_tx_skb(struct iwl_mvm *mvm, struct sk_buff
*skb,
if (WARN_ON_ONCE(mvmsta->sta_id == IWL_MVM_STATION_COUNT))
return -1;
+ if (!skb_is_gso(skb))
+ return iwl_mvm_tx_csum_and_send(mvm, skb, sta);
+
payload_len = skb_tail_pointer(skb) - skb_transport_header(skb) -
tcp_hdrlen(skb) + skb->data_len;
- if (!skb_is_gso(skb) || payload_len <= skb_shinfo(skb)->gso_size) {
- if (skb->ip_summed == CHECKSUM_PARTIAL) {
- int offs = skb_checksum_start_offset(skb);
- int csum_offs = offs + skb->csum_offset;
- __wsum csum;
-
- if (iwl_skb_ensure_writable(skb, csum_offs +
- sizeof(__sum16)))
- return -1;
-
- csum = skb_checksum(skb, offs, skb->len - offs, 0);
-
- *(__sum16 *)(skb->data + csum_offs) = csum_fold(csum);
- }
-
- return iwl_mvm_tx_mpdu(mvm, skb, sta);
- }
+ /* This packet is smaller than MSS, one MPDU is enough */
+ if (payload_len <= skb_shinfo(skb)->gso_size)
+ return iwl_mvm_tx_csum_and_send(mvm, skb, sta);
__skb_queue_head_init(&mpdus_skbs);
--
2.1.4
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